The invention relates to a method for producing a plastic housing for a housing for a steering gear and to a system for carrying out the method.
A steering system refers to a device that is used in motor vehicles, for example, to influence the driving direction. A steering movement initiated by the driver on a steering wheel is transmitted, among other things, via a steering gear to coupled wheels. These steering gears are typically surrounded by a housing.
Aluminum die cast housings are used as the steering housing in most housings for steering gears, which are supplemented with plastic housings. The connection between the aluminum housings and the plastic housings is often achieved by bolts. The boreholes in the plastic housing are typically reinforced by metal sleeves to prevent the plastic material from creeping, with consequent loosening of the bolts. An O-ring, which is a technologically mature seal, is often used to seal the plastic housing with respect to the aluminum housing. O-rings are annular sealing elements having round or O-shaped cross-sections.
To ensure that the O-ring seal functions reliably in the customary vehicle temperature range of 40° C. to +120° C., the plastic material used must exhibit thermal expansion similar to that of the aluminum. Moreover, the plastic material must satisfy the strength requirements of the steering system in the vehicle. For this reason, in many embodiments, the plastic materials are reinforced with fillers.
In general applications, plastic materials are often joined to other components by way of snap-fit elements. To this end, a plastic tab is stretched and then engages in an undercut of the other component. The good elasticity of the plastic material is utilized for this purpose. If snap-fit elements are to be used for the connection in a steering gear, the plastic tabs must be very long since the flexibility of reinforced plastic materials is drastically reduced. However, typically no installation space is provided in the vehicle for these long plastic tabs.
Moreover, it must be noted that the fixation of the plastic parts, such as of the plastic housings on the steering housing, should be secure and cost-effective. This can likewise be achieved by snap-fit elements. These snap-fit elements must be displaceable relative to the base body of the plastic housing and radially move into a groove of the steering housing, so as to be able to ensure secure fixation of the plastic housing.